<script>
    var username = '张三';
    var age = 18;

    function say(provice, city) {
        console.log('this=', this);
        console.log(`我来自${provice}${city}`);
        console.log(`我叫${this.username},今年${this.age}岁`);
    }

    var person = {
        username: '老胡',
        age: 100
    };

    // 调用say()时,this指向了谁?
    say('广东', '深圳');
    // 使用say.call()时,this指向了谁
    say.call(person, '广西', '贵港');
    // 使用apply.call()时,this指向了谁
    say.apply(person, ['广西', '贵港']);
</script>